The failure mode of authoritarian communist regimes was simple. They failed in the same way that authoritarian capitalist regimes like the Pinochet's Chilean go

The failure mode of authoritarian communist regimes was simple. They failed in the same way that authoritarian capitalist regimes like the Pinochet's Chilean government did: the people in power didn't care about the well-being of the general public, and so the economy ultimately collapsed because the needs of the public weren't being met. This is a problem solved by democracy. Now, if you want to argue that there are problems with economic planning, I'm right there with you. I think that market incentives have historically been a more reliable way of running an economy, and that market socialism [1] is a much more viable alternative than a state-planned economy. But it's worth noting that it's hard to make strong claims about the consequences of economic planning when it's never been implemented in a democratic society. Regardless, concerns about the failure modes of authoritarian communist states don't really make sense in the context of market socialism, since it involves neither authoritarianism nor economic planning. [1]: https://en.wikipedia.org/wiki/Market_socialism https://en.wikipedia.org/wiki/Market_socialism